波长调谐移相干涉技术是通过改变光波长来计算相位的。为了减少可调谐激光器在变波长进行移相时光功率的随机变化对相位计算产生的误差, 本文提出了一套光强实时反馈控制系统和同步校准方案。首先分析了光强在某一范围内的随机变化产生测量误差, 并选用合适的光电检测设备搭建了一套光强控制系统。该系统能够将光信号转化为电信号, 并通过PID来实现对光强的控制。实验结果表明, 本系统能够将光强的变化范围控制在±0.002 mW以内, 其响应速度达到600 kHz, 已远远超过干涉仪CCD的取图速度。最后, 对口径为50 mm的光学元件进行表面形貌检测, 加入本控制系统后, 面形精度的测量指标PV值和RMS值分别提高了1.53×10-2λ和2.43×10-3λ, 表明本系统在高精度的光学元件检测领域具有重要的实用价值。

Wavelength-tuned phase-shifting interferometry facilitates phase measurement by changing the wavelength of a tunable diode laser. Random variation of the optical power can cause phase errorsduring the phase-shifting process. To address this problem, an optical power real-time feedback control system and synchronous calibration scheme were developed. First, the measurement error caused by random variation of the optical power was analyzed. An optical power control system was then developed by utilizing suitable optoelectronic detection equipment to convert optical signals into electric signals, such that the optical power can be controlled using a PID. The experimental results show that the accuracy of the optical power is ±0.002 mW and the response speed can approach 600 kHz. Finally, the system was evaluated by detecting the optical component surface.When assembling the system, the PV and RMS are improved by 1.53×10-2λ和2.43×10-3λ, respectively. This system has an important role in high-precision optical component detection.